Apparatus and method for refrigerating articles

ABSTRACT

Apparatus and method for refrigerating articles including an insulating chamber, a conveyor for moving articles through the chamber, a liquid spray system for introducing the liquid cryogen such as liquid nitrogen for contact with the articles with resulting generation of cryogen gas through the chamber in a recirculation path that includes a path portion located externally of the chamber and means for collecting liquid cryogen from the chamber in the external path portion for contact with the recirculated fluid cryogen passing therethrough with resulting vaporization of the collected liquid and entrainment of the liquid in the recirculated gas.

United States Patent [19] Wagner [111 3,871,186 [451 Mar. 18, 1975 APPARATUS AND METHOD FOR REFRIGERATING ARTICLES [75] Inventor: Richard C. Wagner, Darien, Ill.

[73] Assignee: Integral Process Systems, Inc., Park Forest, Ill.

22 Filed: Aug. 23, 1973 21 AppL NOJ 390,755

Primary ExaminerMeyer Perlin Assistant Examiner Ronald CI Capossela Attorney, Agent, or Firm-Hofgren, Wegner, Allen, Stellman & McCord [57] ABSTRACT Apparatus and method for refrigerating articles including an insulating chamber, a conveyor for moving articles through the chamber, a liquid spray system for introducing the liquid cryogen such as liquid nitrogen for contact with the articles with resulting generation of cryogen gas through the chamber in a recirculation path that includes a path portion located externally of the chamber and means for collecting liquid cryogen from the chamber in the external path portion for contact with the recirculated fluid cryogen passing therethrough with resulting vaporization of the collected liquid and entrainment of the liquid in the recirculated gas.

14 Claims, 10 Drawing Figures FK'ENTEB MAR 1 8 1975 saw 2 0F U a on PATEMEU MAR 1 8 ISYS saw u or A APPARATUS AND METHOD FOR REFRIGERATING ARTICLES BACKGROUND OF THE INVENTION One of the features of this invention is to provide an apparatus for refrigerating articles and particularly for freezing them in which a liquid cryogen is sprayed or otherwise contacted with the articles with the resulting production of cryogen gas together with means for recirculating a portion of the gas through the chamber for more efficient refrigeration including a recirculation path portion externally of the chamber together with means for collecting excess liquid cryogen from the spraying and directing it into the external path portion for contact with the recirculated cryogen gas.

Another feature of the invention is to provide a method of refrigerating articles including the recirculating of the gas and the collecting of excess liquid in a portion of the recirculation path externally of the chamber.

The most pertinent prior art of which applicant is aware are prior U.S. Pats. Nos. 3,287,932, 3,298,188, 3,345,828 and 3,403,527 which, however, do not disclose the features of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS tional view taken substantially along line 5-5 of- FIG. 7.

FIG. 6 is a vertical sectional view taken substantially along line 66 of FIG. 2b.

FIG. 7 is a vertical sectional view taken substantially along line 7-7 of FIG. 2b.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment shown in the drawings the apparatus 10 for refrigerating articles comprises an elongated freezing tunnel 11 or chamber having top 12, bottom 13 and side 14 and 15 insulated walls. The top insulated walls 12 are in the form of hinged lids 16 which may be raised and lowered by means of hydraulic cylinders 17, in the customary manner, of which only two are illustrated in FIGS. la and 1b and which are illustrated in side elevation in FIGS. 5 and 6.

Positioned within the chamber or tunnel 11 between an entrance 18 and an exit 19 thereto is a customary conveyor 20 for conveying articles in the chamber in a path coinciding with the upper reach 21 of the conveyor between the entrance and exit. One such article is illustrated schematically at 22 in FIG. 20.

In the illustrated embodiment the fluid cryogen is a liquid of which liquid nitrogen is an excellent example that is introduced into contact with the articles traveling on the conveyor to generate a gas and with the liquid being in excess. The fluid cryogen also includes the gas itself caused by the liquid vaporizing on heat extracted from the articles. As is shown most clearly in FIGS. 2a and 4, a liquid cryogen is introduced by means of a liquid flow means 23 which as illustrated is an assembly of nozzles 24 arranged in the assembly 23 and spaced longitudinally and transversely of the chamber.

Thus in the illustrated embodiment of FIG. 4 there are six nozzles spanning the width of the chamber 11 and eight nozzles arranged longitudinally in each row as shown in FIG. 2a. The liquid cryogen is supplied to the nozzle assembly by means of a pipe 25 which communicates with the piping 26 interconnecting the nozzles 24 by means of a flexible hose 27. With this ur rangement the entire liquid flow assembly 23 may be removed for cleaning when the lids or top walls 12 are raised without requiring dismantling of the assembly 23.

In order to aid in the heat transfer the cryogen gas is recirculated over the articles within the chamber 11. This recirculation aids the intimate contact with the articles particularly where the conveyor 20 is of the preferred open mesh metal construction. The recirculating means comprises a horizontal baffle 28 beneath the conveyor 20 and thus beneath the articles 22 conveyed thereon with this baffle 28 having an end 29 adjacent to but short of the entrance end 18 of the tunnel 11. The recirculation flow which is caused by the rotatable blower 30 is in a path illustrated by the recirculation arrows 31 as shown in FIGS. 2!), 2c, 5, 6 and 7.-

The recirculation path as is illustrated most clearly in FIGS. 2b and 6 includes a path portion 32 located externally of the chamber 11. Thus as shown in FIG. 6 this recirculation portion is located beneath and to the side of the apparatus 10 and communicates with the bottom of the chamber 11 by means ofa vertical fitting 33 that causes gas to flow vertically downwardly into the external portion 32 and upwardly at the side through a passage 34 into the blower 30 where the recirculated gas is introduced laterally back into the tun-.

no] where it is deflected by curved spaced vanes 35 for longitudinal flow toward the entrance 18 as illustrated in FIG. 5.

Beneath the spray head assembly 23 there is provided a baffle 36 in two overlapping sections as shown in FIG. 2a for ease in cleaning with this baffle 36 being sloped toward the recirculation path portion 32 which being beneath the chamber 11 functions as a sump to collect any excess and unevaporated liquid cryogen illustrated schematically at 37 in FIG. 6. The result is that the recirculated external cryogen gas shown at 31 in FIG. 6

' picks up the liquid 37 in the form of small droplets and reintroduces it back into the tunnel II at the turning vanes 35.

A portion of the liquid 37 will of course be evaporated by the recirculating portion of the gas 31 but any unevaporated liquid is physically picked up in the form of droplets and carried back into the tunnel for refrigerating articles carried therethrough. Because the re circulation path portion 32 is at a lower level than the chamber 11 and because of the sloped nature of the baffle 36 the excess cryogen is collected by gravity flow and is redistributed without requiring a separate pump as has been required heretofore.

Communicating with the tunnel or chamber 11 adjacent the entrance 18 are gas evacuation means 38 for exhausting the cryogen gas after the refrigeration in the customary manner as illustrated schematically by the arrow 39. The baffle 28 which is adjacent the entrance 18 to the tunnel and therefore adjacent the gas evacuation means 38 separates the chamber 11 into upper 40 and lower 41 gas recirculation sections of the internal recirculation loop 31. As illustrated in FIGS. 2b and 20 this provides countercurrent flow with respect to the direction of movement of the articles 32 gas contact with the articles.

Provided in the chamber 11 above the conveyor 20 and in communication with the upper recirculation section or space 40 are a plurality of gas moving devices 42 here shown as vertical axis fans for providing axial flow illustrated by the arrows 43. These fans 42 are longitudinally spaced from each other and in the illustrated embodiment are six in number although more or less can be used depending upon the desired capacity of the apparatus.

As illustrated by the arrows 43 in FIG. 2b the exhaust from the fans is downwardly through the conveyor and over the articles 22 carried thereon and is then directed back upwardly by impingement upon the baffle 28. The fans 42 serve as turbulizers to obtain better heat transfer between the articles conveyed through the tunnel by the conveyor 20 and the gas. This results in the exhaust' gases illustrated at 39 in FIG. 20 having a higher temperature caused by heat extracted from the entering articles 22. Thus in one embodiment of the apparatus of this invention the temperature of the exhaust gases 39 was not more than 60 less than the temperature of the incoming articles 22. Furthermore, the transverse or in this embodiment vertical exhaust from the axial flow fans 44 is in a direction transverse to the longitudinal recirculation flow 31 with the combination of gas flows at 90 to each other increasing the turbulence with corresponding increases in heat transfer so that a shorter tunnel 11 may be employed for a given refrigerating capacity.

The apparatus is constructed in separable sections for cleaning. Such a separable arrangement is disclosed in my prior US. Pat. No. 3,580,000.

Various parts of the apparatus shown in the drawings are similar to corresponding parts of my earlier copending applications Ser. No. 264,!33, filed June 19, 1972 now US. Pat. No. 3,824,806, and Ser. No. 339,395, filed Mar. 8, I973, with both applications being assigned to the same assignee as the present application.

Having described my invention as related to the embodiment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the appended claims.

1. Apparatus for refrigerating articles, comprising: means defining an insulated chamber having an entrance and an exit for said articles; conveyor means for moving said articles in the chamber in a path from the entrance to the exit; liquid flow means for introducing a liquid cryogen into said chamber for contact with said articles at an introduction area spaced from said entrance with resulting generation of cryogen gas; means between said introduction area and entrance for recirculating cryogen gas from said chamber in a recirculation path including a path portion located externally of the chamber; and means for collecting any remaining liquid cryogen from said chamber in said external path portion for contact with the recirculated cryogen g'as passing therethrough.

2. The apparatus of claim 1 wherein said chamber is provided with baffle means beneath said liquid flow means sloped toward said enternal path portion for directing liquid cryogen into said path portion as a sump for contact with recirculated gas in said path portion.

3. The apparatus of claim 1 wherein said external path portion includes a part at a lower level than said chamber and thereby operating as a gravity flow liquid collecting sump.

4. The apparatus of claim 1 wherein said liquid flow means comprises spray apparatus located between said chamber exit and said recirculating path portion for spraying liquid cryogen in contact with said articles and including a flexible conduit to an external source of liquid cryogen for removal of said apparatus for cleaning, servicing and the like without requiring dismantling.

5. The apparatus of claim 1 wherein there are provided in said chamber adjacent its entrance evacuation means for exhausting spent cryogen gas and a baffle within the chamber extending to adjacent the evacuation means for separating the chamber into upper and lower recirculation sections of an internal recirculation loop that extends within the chamber toward said evacuation means for countercurrent gas contact with said articles.

6. The apparatus of claim 5 wherein there are provided in said chamber above the baffle and downstream with respect to the path of movement of said articles a plurality of gas moving devices means for creating cross flow of gaseous cryogen over and between said articles.

7. The apparatus of claim 6 wherein said plurality of gas moving devices comprise axial flow fans spaced along a substantial portion of said chamber and exhausting transversely to said path of the articles.

8. The apparatus of claim 7 wherein said evacuation means is located adjacent to said chamber entrance, said plurality of fans are arranged in series along a portion of the chamber between said withdrawal area and said recirculating path portion, and said liquid flow means is located between said recirculation path and said chamber exit.

9. The apparatus of claim 8 wherein said chamber is provided wtih baffle means beneath said liquid flow means sloped toward said external path portion for directing liquid cryogen into said path portion as a sump for contact with recirculated gas in said path portion.

10. The method of refrigerating articles in an insulated chamber having an entrance and an exit and liquid flow means for introducing a liquid cryogen into said chamber for contact with said articles in an excessive amount so as to provide both cryogen liquid and cryogen gas from said liquid in the chamber, comprising: recirculating said cryogen gas into contact with articles within the chamber in a recirculation path including a path portion located externally of the chamber and collecting any remaining liquid cryogen from the chamber in the recirculation path portion for contact by said recirculated gas and redistribution of the liquid in conjunction with the gas back into the chamber.

11. The method of claim 10 wherein said pathportion is at a lower level than said chamber to function as a sump and said liquid is collected therein by gravity flow from the insulated chamber.

12. Apparatus for refrigerating articles, comprising: means defining an insulated chamber having an entrance and an exit for said articles; conveyor means for moving said articles in the chamber in a path from the entrance to the exit; and liquid flow means for introducing a liquid cryogen into said chamber for contact with said articles at an introduction area spaced from said entrance with resulting generation of cryogen gas, said liquid flow means comprising spray apparatus located between said chamber exit and said recirculating path portion for spraying liquid cryogen in contact with said articles and including a flexible conduit to an external source of liquid cryogen for removal of said apparatus for cleaning, servicing and the like without requiring dismantling.

13. Apparatus for refrigerating articles, comprising: means defining an insulated chamber having an entrance and an exit for said articles; conveyor means for moving said articles in the chamber in a path from the entrance to the exit; fluid flow means for introducing hausting transversely to said path of the articles.

l l l l= 

1. Apparatus for refrigerating articles, comprising: means defining an insulated chamber having an entrance and an exit for said articles; conveyor means for moving said articles in the chamber in a path from the entrance to the exit; liquid flow means for introducing a liquid cryogen into said chamber for contact with said articles at an introduction area spaced from said entrance with resulting generation of cryogen gas; means between said introduction area and entrance for recirculating cryogen gas from said chamber in a recirculation path including a path portion located externally of the chamber; and means for collecting any remaining liquid cryogen from said chamber in said external path portion for contact with the recirculated cryogen gas passing therethrough.
 2. The apparatus of claim 1 wherein said chamber is provided with baffle means beneath said liquid flow means sloped toward said enternal path portion for directing liquid cryogen into said path portion as a sump for contact with recirculated gas in said path portion.
 3. The apparatus of claim 1 wherein said external path portion includes a part at a lower level than said chamber and thereby operating as a gravity flow liquid collecting sump.
 4. The apparatus of claim 1 wherein said liquid flow means comprises spray apparatus located between said chamber exit and said recirculating path portion for spraying liquid cryogen in contact with said articles and including a flexible conduit to an external source of liquid cryogen for removal of said apparatus for cleaning, servicing and tHe like without requiring dismantling.
 5. The apparatus of claim 1 wherein there are provided in said chamber adjacent its entrance evacuation means for exhausting spent cryogen gas and a baffle within the chamber extending to adjacent the evacuation means for separating the chamber into upper and lower recirculation sections of an internal recirculation loop that extends within the chamber toward said evacuation means for countercurrent gas contact with said articles.
 6. The apparatus of claim 5 wherein there are provided in said chamber above the baffle and downstream with respect to the path of movement of said articles a plurality of gas moving devices means for creating cross flow of gaseous cryogen over and between said articles.
 7. The apparatus of claim 6 wherein said plurality of gas moving devices comprise axial flow fans spaced along a substantial portion of said chamber and exhausting transversely to said path of the articles.
 8. The apparatus of claim 7 wherein said evacuation means is located adjacent to said chamber entrance, said plurality of fans are arranged in series along a portion of the chamber between said withdrawal area and said recirculating path portion, and said liquid flow means is located between said recirculation path and said chamber exit.
 9. The apparatus of claim 8 wherein said chamber is provided wtih baffle means beneath said liquid flow means sloped toward said external path portion for directing liquid cryogen into said path portion as a sump for contact with recirculated gas in said path portion.
 10. The method of refrigerating articles in an insulated chamber having an entrance and an exit and liquid flow means for introducing a liquid cryogen into said chamber for contact with said articles in an excessive amount so as to provide both cryogen liquid and cryogen gas from said liquid in the chamber, comprising: recirculating said cryogen gas into contact with articles within the chamber in a recirculation path including a path portion located externally of the chamber and collecting any remaining liquid cryogen from the chamber in the recirculation path portion for contact by said recirculated gas and redistribution of the liquid in conjunction with the gas back into the chamber.
 11. The method of claim 10 wherein said path portion is at a lower level than said chamber to function as a sump and said liquid is collected therein by gravity flow from the insulated chamber.
 12. Apparatus for refrigerating articles, comprising: means defining an insulated chamber having an entrance and an exit for said articles; conveyor means for moving said articles in the chamber in a path from the entrance to the exit; and liquid flow means for introducing a liquid cryogen into said chamber for contact with said articles at an introduction area spaced from said entrance with resulting generation of cryogen gas, said liquid flow means comprising spray apparatus located between said chamber exit and said recirculating path portion for spraying liquid cryogen in contact with said articles and including a flexible conduit to an external source of liquid cryogen for removal of said apparatus for cleaning, servicing and the like without requiring dismantling.
 13. Apparatus for refrigerating articles, comprising: means defining an insulated chamber having an entrance and an exit for said articles; conveyor means for moving said articles in the chamber in a path from the entrance to the exit; fluid flow means for introducing a fluid cryogen into said chamber for contact with said articles at an introduction area spaced from said entrance; means for circulating gaseous cryogen from said fluid in countercurrent with said articles; and a plurality of gas moving device means between said introduction area for said cryogen and said entrance for creating cross flow of gaseous cryogen over and between said articles.
 14. The apparatus of claim 13 wherein said plurality of gas moving devices comprise axial flow fans spaced along a subsTantial portion of said chamber and exhausting transversely to said path of the articles. 